In a fiber placement machine, multiple tows, or rovings, of fiber reinforced pre-pregged resin run side-by-side from a tow supply source (typically a creel having several spools of tow material) to a work zone, the tows being applied by a tow dispensing head. The tows may pass over several redirect roller sets while running from the supply to the head. The roller sets have closely-spaced independent grooved rollers, providing short, upstanding flanges at either side of the tow for guidance and containment. In a machine such as the FPX fiber placement machine, available from Cincinnati Milacron Inc., the subject matter of U.S. Pat. No. 5,022,952, the head is maneuvered through a variety of spatial orientations relative to the creel, thus drastically changing the tow path and, potentially creating momentary slack in the tows. It has, therefore, been determined that it would be beneficial to have more guiding surface at the sides of a tow. However, if the roller flanges are increased in diameter, the relatively narrow, very deep, roller groove would be substantially more difficult to manufacture. And, owing to the very close spacing of the rollers, the increased outer flange surfaces would necessitate a finishing to high degree of flatness and squareness, the larger rollers being less tolerant to flange run-out. Since the usual case finds the tow well-seated in the roller groove, it is preferred that increased side guidance be provided at a relatively low cost for materials and assembly effort.
This invention achieves the goal of having increased side guidance for a tow running along a tow path from a creel to a dispensing head, while obviating the previously mentioned difficulties inherent in having a narrow grooved roller with increased flange diameters.